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Growth and Characterization of a New Superconductor GaBa2Ca3Cu4O11+δ
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作者 明学 何成平 +2 位作者 祝熙宇 缑慧阳 闻海虎 《Chinese Physics Letters》 SCIE EI CAS CSCD 2023年第1期60-64,共5页
We successfully grow a new superconductor GaBa2Ca3Cu4O11+δ(Ga-1234) with a transition temperature of 113 K, using the Walker-type high-pressure synthesis apparatus. X-ray diffraction measurements on the powderized sa... We successfully grow a new superconductor GaBa2Ca3Cu4O11+δ(Ga-1234) with a transition temperature of 113 K, using the Walker-type high-pressure synthesis apparatus. X-ray diffraction measurements on the powderized samples show a mixture of the Ga-1234 phase and the Ca0.85CuO2phase, and the former is dominant. Under the scanning electron microscope, plate-like crystals of the Ga-based 1234 phase with shiny surfaces can be seen.The obtained local chemical compositions revealed by energy dispersion x-ray spectroscopy are very close to the stoichiometric values. On some sub-millimeter crystal-like samples of the 1234 phase, we obtain a full Meissner shielding volume. From the temperature-dependent magnetizations, we determine the irreversibility fields and find that the system exhibits a highly anisotropic behavior. 展开更多
关键词 Cu4 PHASE SUPERCONDUCTOR
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Contrasting physical properties of the trilayer nickelates Nd4Ni3O10 and Nd4Ni3O8 被引量:2
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作者 Qing Li chengping he +3 位作者 XiYu Zhu Jin Si XinWei Fan Hai-Hu Wen 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2021年第2期98-104,共7页
We report the crystal structures and physical properties of trilayer nickelates Nd4Ni3O10and Nd4Ni3O8.Measurements of magnetization and electrical resistivity display contrasting behaviors in the two compounds.Nd4Ni3O... We report the crystal structures and physical properties of trilayer nickelates Nd4Ni3O10and Nd4Ni3O8.Measurements of magnetization and electrical resistivity display contrasting behaviors in the two compounds.Nd4Ni3O10shows a paramagnetic metallic behavior with a metal-to-metal phase transition(T^*)at about 162 K,as revealed by both magnetic susceptibility and resistivity.Further magnetoresistance and Hall coefficient results show a negative magnetoresistance at low temperatures and the carrier type of Nd4Ni3O10is dominated by hole-type charge carriers.The significant enhancement of Hall coefficient and resistivity below T*suggests that effective charge carrier density decreases when cooling through the transition temperature.In contrast,Nd4Ni3O8 shows an insulating behavior.In addition,this compound shows a paramagnetic behavior with the similar magnetic moment as that of Nd4Ni3O10derived from the Curie-Weiss fitting.This may suggest that the magnetic moments in both systems are contributed by Nd^3+ ions.By applying pressures up to about 49 GPa,the insulating behavior is still present and becomes even stronger under a high pressure.Our results suggest that the different Ni configurations(Ni^1+/2+ or Ni^2+/3+)and the changes of coordination environment of Ni sites may account for the contrasting behaviors in trilayer nickelates Nd4Ni3O10and Nd4Ni3O8. 展开更多
关键词 trilayer nickelate Nd4Ni3O10 and Nd4Ni3O8 high-pressure study
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Pressure induced color change and evolution of metallic behavior in nitrogen-doped lutetium hydride 被引量:3
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作者 Ying-Jie Zhang Xue Ming +6 位作者 Qing Li Xiyu Zhu Bo Zheng Yuecong Liu chengping he Huan Yang Hai-Hu Wen 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2023年第8期125-130,共6页
By applying pressures up to 42 GPa on the nitrogen-doped lutetium hydride(LuH2_(±x)N_(y)),we have found a gradual change of color from dark-blue to pink-violet in the pressure region of about 12 to 21 GPa.The tem... By applying pressures up to 42 GPa on the nitrogen-doped lutetium hydride(LuH2_(±x)N_(y)),we have found a gradual change of color from dark-blue to pink-violet in the pressure region of about 12 to 21 GPa.The temperature dependence of resistivity under pressures up to 50.5 GPa shows progressively optimized metallic behavior with pressure.Interestingly,in the pressure region for the color change,a clear decrease of resistivity is observed with the increase of pressure,which is accompanied by a clear increase of the residual resistivity ratio(RRR).Fitting to the low temperature resistivity gives exponents of about 2,suggesting a Fermi-liquid behavior in the low temperature region.The general behavior in a wide temperature region suggests that the electron-phonon scattering is still the dominant one.The magnetoresistance up to 9 T in the state under a pressure of 50.5 GPa shows an almost negligible effect,which suggests that the electric conduction in the pink-violet state is dominated by a single band.It is highly desired to have theoretical efforts in understanding the evolution of color and resistivity in this interesting system. 展开更多
关键词 nitrogen-doped lutetium hydride room temperature superconductivity high-pressure technique color change
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Discovery of a new nontoxic cuprate superconducting system Ga-Ba-Ca-Cu-O
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作者 Yue Zhang Wenhao Liu +4 位作者 Jin Si Xiyu Zhu chengping he Haonan Zhao Hai-Hu Wen 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2018年第9期82-85,共4页
Superconductivity is observed in a new nontoxic cuprate system Ga-Ba-Ca-Cu-O,with T_c=82 K for Ga Ba_2Ca_5Cu_6O_(14+δ)(Ga-1256)and T_c=116 K probably for Ga Ba_2Ca_3Cu_4O_(10+δ)(Ga-1234)or Ga Ba_2Ca_2Cu_3O_(8+δ)(Ga... Superconductivity is observed in a new nontoxic cuprate system Ga-Ba-Ca-Cu-O,with T_c=82 K for Ga Ba_2Ca_5Cu_6O_(14+δ)(Ga-1256)and T_c=116 K probably for Ga Ba_2Ca_3Cu_4O_(10+δ)(Ga-1234)or Ga Ba_2Ca_2Cu_3O_(8+δ)(Ga-1223),respectively.All compounds are fabricated by solid state reaction method under high pressure and high temperature.Samples are characterized by resistivity,magnetization and X-ray diffraction(XRD)measurements.The temperature dependence of magnetization measured in both zero-field-cooled and field-cooled processes on one sample(S1)shows two superconducting transitions at about 82 K and113 K.The estimated shielding fraction for the phase with T_cof 82 K is about 67%,while the fraction for another phase with T_(c )of 113 K is quite small.The XRD Rietveld refinement for S1 indicates two main phases existing in the sample,Ga-1256 with fraction of about 58%and non-superconducting Ca_(0.85)Cu O_2with fraction of about 42%respectively.Thus,we can conclude the superconducting phase with transition temperature of 82 K is due to Ga-1256.The resistivity measurement also confirms the superconductivity for S1,and the resistivity reaches zero at about 82 K.The temperature dependence of magnetization for another sample(S2)shows much higher superconducting shielding fraction for the phase with T_cof 116 K,which may be a promising prospective for the synthesis of Ga-1234 or Ga-1223 phase. 展开更多
关键词 CUPRATES high pressure and high temperature SUPERCONDUCTIVITY
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